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Probing the interphase “HO zone” originated by carbon nanotube during catalytic ozonation
Ist Teil von
Water research (Oxford), 2017-10, Vol.122, p.86-95
Ort / Verlag
England: Elsevier Ltd
Erscheinungsjahr
2017
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
Carbon nanotube (CNT) is an attractive metal-free catalyst that can be explored in combination with ozone treatment. Using fluorescence microscopy image analysis, we investigated the production of hydroxyl radicals (HO) within the solid-liquid interphase for CNT-mediated catalytic ozonation. The visualized results suggest that HO was vastly generated via catalysis and accumulated within a surface region of the CNT (we defined this region as the interphase “HO zone”). In this region, using 7-hydroxycoumarin as a HO marker, the radical abundance was at least 1000 times higher than that in the aqueous bulk phase. Owing to the observed inhomogeneity of HO, the CNT/ozone system effectively decomposed perfluorooctane sulfonate that was fairly resistant to non-catalytic ozonation, and the decomposition kinetics was not much inhibited by tert-butanol as bulk-phase HO scavenger due to the remaining “HO zone” at surface region available for reaction. A longevity trial revealed the sustained formation of the interphase “HO zone” and strongly indicated that the graphitic structure may optimize the density of surface active sites responsible for the proliferation and local concentration of HO. CNT, with good catalytic efficiency, longevity and stability, is anticipated as the basis of future nanomaterials able to promote HO exposure in ozone treatment for advanced oxidation process.
A schematic diagram describing the formation of the interphase “HO zone” via CNT-mediated catalytic ozonation. [Display omitted]
•Fluorescence microscopy image analysis is explored to characterize interphase HO.•An interphase “HO zone” with concentrated HO was visualized in CNT/O3 system.•The interphase “HO zone” encircling CNT remarkably enhanced the kinetics of AOPs.•Graphitic carbon of CNT induces the sustained formation of interphase “HO zone”.